The present invention relates to the testing of telecommunication networks, and more particularly to a method for emulating a terminal for testing a telecommunication network and to a corresponding test apparatus for testing a telecommunication network.
In telecommunication networks, particularly also in open communication systems, digital data are usually transmitted according to specified rules. One form of such rules are so-called protocols. For testing telecommunication networks, test apparatuses, often so-called protocol testers, are used that can be configured with respect to the protocol used in the network. Examples include the protocols GSM, ISDN, GPS, UMTS, CDMA, ISUP.
To outline the problem underlying the invention, the following will first explain a protocol tester known from the state of the art, sold by the applicant of the present application under the name Tektronix K1297. To test a telecommunication network, the protocol tester is connected to said telecommunication network. The term xe2x80x9ctestxe2x80x9d comprises very different forms of testing, only one of which, however, will be looked at in detail below. The K1297 referred to above comprises a screen on which the user can create a test scenario. A test scenario is entered using the keyboard and/or the computer mouse. FIG. 1 shows a user interface known from the K1297, the so-called Diagram View, as can be seen from the bottom left-hand corner of FIG. 1. In a top area and a right-hand area of the user interface there are icons, which by clicking on them lead to menus being opened in the known manner that support the user in setting up a test scenario. Since they are of secondary importance for the following, they are not described here in greater detail.
The architecture model for so-called open communication systems was developed by the International Standardization Organization, ISO. The OSI (Open Systems Interconnection) reference model breaks down the necessary functions into a hierarchical layer structure. It is this layer structure which the setting-up of a test scenario in a protocol tester has to follow. In FIG. 1 the so-called protocol stack created by a user is marked 12, this figure showing as an example a protocol stack for testing a communication organized according to the ISDN protocol. A bottom-most layer 14 serves to take into account layer 1, i.e., the bit transfer layer (physical layer) and the transmission medium including the cables, cable ports, etc. used. This is followed by several layers, 16, depending on which layer level the test is to take place. In the present example a second layer (isdnl2=ISDN Layer 2) 16a and a third layer (isdnl3) 16b are shown. The suffix xe2x80x9cxe2x88x92texe2x80x9d at the third layer 16b indicates that in the present case the terminal side is to be emulated by the protocol tester (te=terminal), it also being possible for a protocol tester of this kind to be used for emulating the network side, which would then be marked by a suffix xe2x80x9cxe2x88x92et.xe2x80x9d The third layer 16b is followed by the ISDN terminal layer 18, which provides an adaptation to the third layer 16b located below it, and to a user interface (USIM) 20 located above it. Via the user interface 20 test scenarios desired by a user may be entered into the protocol tester, particularly by designing so-called terminals, one of which is in each case assigned to the test communication. For each user interface 20 up to 240 terminals may be programmed. The user interface is assigned a terminal layer 18.
Although FIG. 2 already exhibits features of the present invention, the user interface Parameter View 22 shown, particularly its left-hand window 24, may serve to describe further the setting up of a test with the known protocol tester K1297. As can be seen from said window 24 the protocol tester in the protocol stack to be emulated includes the emulation of layer 14 of layer 16a, of layer 16b and of the terminal layer 18. The user interface 20 allows general specification data to be given in a menu item (general) 22 and the traffic taking place on the communication network to be specified in a menu item (traffic profile) 25. A menu item (users) 26 allows the behavior of the terminals (terminals) involved in the communication to be specified. It is possible to specify that all terminals execute the same test, i.e., have the same test communication sequence, see menu item 28, and/or individual terminals or groups of terminals may be assigned other communication sequences. For this purpose, menu items U1_10, U11_30, U31_60, U61_100 and U101_240 are given, with U meaning user=terminal and the numbers corresponding to the associated terminals numbered consecutively. In the case shown in FIG. 2, terminal 1 (see dark background of menu item 30) is to be assigned a test communication sequence.
The user may now choose between manual and automatic execution of a test. With reference to FIG. 2, in the top right-hand window 32 the manual mode may be selected via menu item 34. In the manual mode actions may be selected via other menu items, such as menu item 36 (offhook=lift [a receiver]) and menu item 38 (onhook=put down [a receiver]). When the relevant menu item is clicked, the respective action is executed for the specified terminal 30. Special functions may be entered via a menu item 40 (feature button). Via a menu item 42 the automatic mode may be selected. In the state of the art, with K1297 in its known embodiment, one of two firmly specified test scenarios may be chosen in the automatic mode: in the first scenario a terminal offhooks, makes a call on its own within a specified period of time, waits a specified period of time, and then onhooks. After a specifiable period of time the test starts anew. In the second firmly specified test scenario, a terminal is called, offhooks after a specified period of time, and onhooks after a specifiable time. A time period after which this sequence is repeated may be set.
The disadvantage of this solution is that the two firmly specified test scenarios, which may be selected in the automatic mode, are sufficient for some test cases, but some wishes remain unsatisfied. For supplementary services, for example, such as xe2x80x98call waitingxe2x80x99 or xe2x80x98brokers callxe2x80x99, there are no sufficient test opportunities. Also, defective calls, when only a part of the number is dialled, cannot be simulated in the automatic mode.
Running such tests in the manual mode would be extremely complex and time-consuming to program, particularly for several terminals in the test communication network, so that there is no realistic way of running the mentioned tests. However, plausible statements concerning the operability of a communication network may only be made if the tests to be executed come close to the conditions encountered in actual practice. It is particularly important to determine the maximum load carrying capacity of a telecommunication network. This is the only way to determine up to which limit the operability of the telecommunications network can be guaranteed.
What is desired is a method for emulating a terminal for testing a communication network which significantly expands the possibilities of the tests to be executed as well as a corresponding test apparatus.
Accordingly the present invention provides a method for emulating a terminal for testing a communication network, said terminal being assigned a user interface programmable by the user for executing an automatic communication sequence, a large number of keywords being made available for programming said user interface from which a communication sequence of at least one terminal in the automatic communication sequence may be compiled, each keyword having a program code correlated with it. Also, an entry mask is provided on a display device into which a user may enter a series of at least two keywords to compile the communication sequence of the at least one terminal. Finally, the program codes that are correlated with the keywords entered into the entry mask by a user are linked to an executable program. A test apparatus for testing a telecommunication network has a storage device in which keywords are filed from which a communication sequence of at least one terminal in a communication may be compiled, and the program code correlated with each keyword. Moreover, the apparatus has a display device with an entry mask into which a series of at least two keywords may be entered by a user for compiling the communication sequence of the at least one terminal. Moreover, the apparatus features a compiling device in which the program code, which is correlated with the keywords entered into the entry mask by the user, may be linked to give an executable program.
The objects, advantages and other novel features of the present invention are apparent from the following detailed description when read in conjunction with the appended claims and attached drawing.